气候变化领域集成服务门户(CCPortal): A constraint upon the basal water distribution and thermal state of the Greenland Ice Sheet from radar bed echoes

CCPortal

DOI	10.5194/tc-12-2831-2018
	A constraint upon the basal water distribution and thermal state of the Greenland Ice Sheet from radar bed echoes
	Jordan T.M.; Williams C.N.; Schroeder D.M.; Martos Y.M.; Cooper M.A.; Siegert M.J.; Paden J.D.; Huybrechts P.; Bamber J.L.
发表日期	2018
ISSN	19940416
卷号	12 期号:9
英文摘要	There is widespread, but often indirect, evidence that a significant fraction of the bed beneath the Greenland Ice Sheet is thawed (at or above the pressure melting point for ice). This includes the beds of major outlet glaciers and their tributaries and a large area around the NorthGRIP borehole in the ice-sheet interior. The ice-sheet-scale distribution of basal water is, however, poorly constrained by existing observations. In principle, airborne radio-echo sounding (RES) enables the detection of basal water from bed-echo reflectivity, but unambiguous mapping is limited by uncertainty in signal attenuation within the ice. Here we introduce a new, RES diagnostic for basal water that is associated with wet-dry transitions in bed material: bed-echo reflectivity variability. This technique acts as a form of edge detector and is a sufficient, but not necessary, criteria for basal water. However, the technique has the advantage of being attenuation insensitive and suited to combined analysis of over a decade of Operation IceBridge survey data. The basal water predictions are compared with existing analyses of the basal thermal state (frozen and thawed beds) and geothermal heat flux. In addition to the outlet glaciers, we demonstrate widespread water storage in the northern and eastern interior. Notably, we observe a quasilinear corridor of basal water extending from NorthGRIP to Petermann Glacier that spatially correlates with elevated heat flux predicted by a recent magnetic model. Finally, with a general aim to stimulate regional- and process-specific investigations, the basal water predictions are compared with bed topography, subglacial flow paths and ice-sheet motion. The basal water distribution, and its relationship with the thermal state, provides a new constraint for numerical models. © Author(s) 2018.
学科领域	basal flow; echo sounding; geothermal gradient; glacier dynamics; heat flux; ice sheet; NorthGRIP; outlier; radar; reflectivity; spatial distribution; thawing; water storage; Arctic; Greenland; Greenland Ice Sheet; Petermann Glacier
语种	英语
scopus关键词	basal flow; echo sounding; geothermal gradient; glacier dynamics; heat flux; ice sheet; NorthGRIP; outlier; radar; reflectivity; spatial distribution; thawing; water storage; Arctic; Greenland; Greenland Ice Sheet; Petermann Glacier
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/119075
作者单位	Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, Bristol, United Kingdom; Department of Geophysics, Stanford University, Stanford, CA, United States; Now at British Geological Survey, Nottingham, United Kingdom; Department of Electrical Engineering, Stanford University, Stanford, CA, United States; Department of Astronomy, University of Maryland, College Park, MD, United States; NASA Goddard Space Flight Center, Greenbelt, MD, United States; Grantham Institute and Department of Earth Science and Engineering, Imperial College, London, United Kingdom; Center for Remote Sensing of Ice Sheets, University of Kansas, Lawrence, United States; Earth System Science and Departement Geografie, Vrije Universiteit Brussel, Brussels, Belgium
推荐引用方式 GB/T 7714	Jordan T.M.,Williams C.N.,Schroeder D.M.,et al. A constraint upon the basal water distribution and thermal state of the Greenland Ice Sheet from radar bed echoes[J],2018,12(9).
APA	Jordan T.M..,Williams C.N..,Schroeder D.M..,Martos Y.M..,Cooper M.A..,...&Bamber J.L..(2018).A constraint upon the basal water distribution and thermal state of the Greenland Ice Sheet from radar bed echoes.Cryosphere,12(9).
MLA	Jordan T.M.,et al."A constraint upon the basal water distribution and thermal state of the Greenland Ice Sheet from radar bed echoes".Cryosphere 12.9(2018).